Local tradition holds that a souterrain sits within a nearby ringfort, and a depression in the earth is said to mark the spot. Whether that dip in the ground reflects a roof slowly giving way over centuries, or simply the memory of digging, is hard to say. Vegetation has since closed over whatever was there, leaving no visible trace.

Souterrains are underground stone-lined passages or chambers, typically associated with Early Medieval ringforts in Ireland, built roughly between the sixth and twelfth centuries. They were used for a variety of purposes, most likely as cool storage spaces and as places of refuge during attack. The ringfort at Carrigfadeen, recorded as CO143-044001, is the kind of enclosed farmstead that was once the most common form of rural settlement across the Irish countryside, and many such enclosures contained souterrains that have since collapsed or been swallowed by growth. At Carrigfadeen, the underground feature survives only in tradition and in that slight, ambiguous depression in the soil.